HP StorageWorks XP Remote Web Console Software - Manual (Page 34)

Pair Status
TrueCopy for Mainframe displays the pair status for each volume in the selected logical CU of the
connected HP disk array. The MCU maintains the status of the M-VOL and is responsible for keeping
the M-VOL and its R-VOL synchronized. The RCU maintains the status of the R-VOL. The MCU can
change the pair status of the M-VOL and R-VOL. The RCU can change the pair status of the R-VOL
but not the M-VOL. The MCU will detect when the RCU changes the R-VOL status (if the path status
is normal) and will change the M-VOL status accordingly. The TrueCopy for Mainframe pair status
can be acquired from the MCU and RCU using the TrueCopy for Mainframe software (Pair Status)
and the CQUERY TSO command.
“TrueCopy for Mainframe Pair Status” (page 34) lists and describes the TrueCopy for Mainframe
pair status descriptions. A volume which is not assigned to a TrueCopy for Mainframe pair has
the status simplex. When a TrueCopy for Mainframe pair is started, the MCU changes the status
of both volumes (M-VOL and R-VOL) to pending duplex. When the initial copy operation is complete,
the MCU changes the status of both volumes to duplex. When a pair is suspended from the MCU,
the MCU changes the status of the M-VOL and R-VOL (if the path status is normal) to suspended.
When a pair is suspended from the RCU, the RCU changes the status of the R-VOL to suspended,
and the MCU detects the pair suspension (if the path status is normal) and changes the M-VOL
status to suspended. When you release a pair from the MCU, the MCU changes the status of the
M-VOL and R-VOL (if the path status is normal) to simplex. When you release a pair from the RCU,
the RCU changes the R-VOL status to simplex, and the MCU detects the pair release (if the path
status is normal) and changes the M-VOL status to suspended.
TrueCopy for Mainframe Asynchronous-Specific Pair Status
The TrueCopy for Mainframe Asynchronous suspending and deleting transitional states occur when
a request to change TrueCopy for Mainframe Asynchronous pair status has been accepted, but
the change to the requested status (suspended or simplex) is not yet complete. These states are not
reported to the host. In the case of suspending, both the user and the MCU can request the status
change. In the case of deleting, only the user can request the status change. If the user requested
the status change, the final status is reported at the end of the transition. If an error caused the
status to change to suspended, the suspended status is reported at the beginning of the transition.
The TrueCopy for Mainframe Asynchronous SEQCHK status is indicated when a TrueCopy for
Mainframe Asynchronous pair assigned to a consistency group with the System timer type accepts
a non-time-stamped update from the primary system. The SEQCHK status does not affect TrueCopy
for Mainframe Asynchronous copy activities and will be removed when the next time-stamped
update is successfully copied to the R-VOL. However, if a disaster or system failure occurs before
the next time-stamped update, the update sequence consistency between the R-VOL and other
R-VOLs in the consistency group is not ensured. To ensure effective disaster recovery, you should
detect and remove the source of the SEQCHK status. The SEQCHK status can be caused by any
of the following:
•
An application may issue update I/Os bypassing the MVS standard I/O procedure.
•
The I/O time-stamping function may not be active at the primary system.
Table 8 TrueCopy for Mainframe Pair Status
Description Pair Status
This volume is not currently assigned to a TrueCopy for
Mainframe pair. When this volume is added to a TrueCopy
for Mainframe pair, its status will change to pending
duplex. Simplex
The TrueCopy for Mainframe initial copy operation for this
pair is in progress. This pair is not yet synchronized. When
the initial copy is complete, the status changes to duplex. Pending Duplex
34 About TrueCopy for Mainframe Operations